What is number three copper

I deal with a lot with number one and number two copper. But I keep hearing about number three copper. What is it and is it worth anything and where would it be obtained.

I usually see stuff like very thin stripped wire or thin copper roofing going as this grade. I have also seen some yards refer to computer wire as #3 insulated.

I think like most things, it depends on the yard. Around here #3 copper is sheet copper, roofing, lightning rods, tea kettles, pots & pans, etc.

I had understood it to be wire with less than 30% recovery. It's less valuable than shop wire but over things like string lights and coax cable.

There can be #3 insulated, and also #3 non-insulated copper. I think the standard for it is 85% copper for the non-insulated but that doesn't mean the scrap yard goes that low. For example, an almost all copper heatsink (fins and base) but a bit of aluminum on it.